Determining which type of material handling methods and storage are required for fast moving and high inventory SKUs is not a simple task.
We know we can increase the number of pallet positions in a given footprint by stacking pallets on the floor or by utilizing drive-in racks but these options come with utilization and productivity drawbacks as noted here.
A good compromise is to have Double-Deep or Push-Back racking. Typically, double deep racking with a double deep reach truck is less expensive than going with push-back racking but order selection productivity is better with push-back racks. However pallets must be removed by either a fork-lift or physically pulled out by another operator, which in turn brings ergonomics and safety concerns. Ultimately, the qualitative/quantitative pros & cons will vary from site to site.
The following will focus on double-deep racking only; mainly due to the fact that the additional cost of a double-deep reach mechanism on a reach truck is usually far cheaper than the additional cost for the push-back carts.
So now you need to incorporate these double-deep racks in you facilities to get good cubic utilization. How can we get the most out of the footprint?
There are two common arrangements for double-deep racks.
- The first is to have a beam off of the floor at around 12” or so, which allows the reach truck outriggers to go under the beam. This however does have some drawbacks such as order selectors having to step onto this level to pick cases from the back pallet (note: walk-in beams do exist) and it leaves the upright subject to repeated hits by the outriggers.
- The second method is to have no beam at this level and to straddle the pallets with the outriggers. However, this requires an increased rack width (typical is 102” c/c). Having no beam at the bottom helps with the selection process and makes removing the empty pallet easier since it can be done with a regular pallet jack. BUT, it still leaves the upright susceptible to hits by the outriggers. And let’s face it; with the heights that we are going with these days, the less obstruction reach truck operators have to deal with, the better.
There is an alternative that combines benefits from both arrangements: density of 96” wide racks (vs. 102”) plus no obstructions to the outriggers without the use of a low beam: “severe cant leg frame” design where the front leg of an upright is swept back 36” from the rack face to a shared rear base plate. It allows clearance for the fork lift outrigger legs on either side of the floor level pallet.
If you do go with the severe cant leg design, make sure that the specifications for both the racking and mobile equipment is well documented and verify the dimensions when the product come through the door before installing them. Even the cant leg will create problems if it’s not designed properly…
When in carpentry, measure twice cut once.
In warehousing, determine the needs, issue the specifications – and then install!